dual SDRAMS

[nadeemtamuk191]

Hi,

I am using a STM32H743BIT6., I am trying to access two SDRAM  part-number(IS42S16320D-7TL)

problem:

both the DRAMS are wring the same data at the same time, so instead of having access to a 32 bit i am getting access to 16bit

help will be apricated

Thank you

[aahsan]

Here is the CubeMX Setting which were used for this test.

@Tesla DeLorean see if you can think of some setting which we might be overlooking here.

[Tesla DeLorean]

https://www.mouser.com/datasheet/2/198/42-45R-S_86400D-16320D-32160D-258456.pdf

Suspect the banking is handled incorrectly

FMC_A14/FMC_BA0

FMC_A15/FMC_BA1

These might be usable interchangeably but I think you'll need to change the A13 pin to use A15 as a source instead.

[aahsan]

Thanks, let me try updating that and see if that can make any difference.

[Tesla DeLorean]

On the BA0/BA1 side for the SDRAM, I don't suppose which 16MB bank matters to the STM32 provided that it decodes consistently

ie, these will be functionally equivalent

BA0 = A14, BA1 = A15

BA0 = A15, BA1 = A14

In terms of modding the circuit to check, changing one wire seemed the easier option.

[nadeemtamuk191]

you mean

SDRAM1

A13-----> BA0

A14-----> BA1

SDRAM2

A14-----> BA0

A13-----> BA1

?

[Tesla DeLorean]

No, I mean the bank ordering [0..3] doesn't particularly matter

STM32 A14 = BA0

STM32 A15 = BA1

You've involved STM32 A13, and I don't think that's correct. As you've got A14 already wired to one of the bank pins my suggestion to test was to cut the wire to the other currently carrying A13, and connect that to A15 instead.

I don't see enough of the circuit/schematic to gauge the difficulty to achieving that.

[nadeemtamuk191]

Hi Tesla DeLorean,

i am attaching a new png file where my A15 is connected to the SRAM. if that won't cause any issues I can modify the change.

[Tesla DeLorean · Accepted solution]

Perhaps easier to lift leg/pin 20 of both SDRAM and connect to FMC_A15_BA1

So you get the 4x 16MB banks decoding

A13 is not a bank pin

13 rows use (A0..A12)

10 columns use (A0..A9)

[nadeemtamuk191]

after doing the change to one SDRAM (SDRAM2) we were only able to memset to 0XFFFFFFFF half the memory of SDRAM2 as shown below

do i need to make the change for both the SDRAMS? as you mention A13 is not a bank pin

how to memset the entire memory?

when i am trying to write the SDRAM1 at address 0X0C00000. i can see that some of the data is getting written on address 0X0C10000.